• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.4
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• pp.1294-1300
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• 2010

In an environment where all nodes move, the sensor node receives anchor node's position information within communication radius and modifies the received anchor node's position information by one's traveled distance and direction in saving in one's memory, where if there at least 3, one's position is determined by performing localization through trilateration. The proposed localization mechanisms have been simulated in the Matlab. In an environment where certain distance is maintained and nodes move towards the same direction, the probability for the sensor node to meet at least 3 anchor nodes with absolute coordinates within 1 hub range is remote. Even if the sensor node has estimated its position with at least 3 beacon information, the angle ${\theta}$ error of accelerator and digital compass will continuously apply by the passage of time in enlarging the error tolerance and its estimated position not being relied. Dead reckoning technology is used as a supplementary position tracking navigation technology in places where GPS doesn't operate, where one's position can be estimated by knowing the distance and direction the node has traveled with acceleration sensor and digital compass. The localization algorithm to be explained is a localization technique that uses Dead reckoning where all nodes are loaded with omnidirectional antenna, and assumes that one's traveling distance and direction can be known with accelerator and digital compass. The simulation results show that our scheme performed better than other mechanisms (e.g. MCL, DV-distance).

• The Journal of Korea Robotics Society
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• v.3 no.3
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• pp.194-202
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• 2008

This paper describes a new method for indoor environment mapping and localization with stereo camera. For environmental modeling, we directly use the depth and color information in image pixels as visual features. Furthermore, only the depth and color information at horizontal centerline in image is used, where optical axis passes through. The usefulness of this method is that we can easily build a measure between modeling and sensing data only on the horizontal centerline. That is because vertical working volume between model and sensing data can be changed according to robot motion. Therefore, we can build a map about indoor environment as compact and efficient representation. Also, based on such nodes and sensing data, we suggest a method for estimating mobile robot positioning with random sampling stochastic algorithm. With basic real experiments, we show that the proposed method can be an effective visual navigation algorithm.

• Journal of Positioning, Navigation, and Timing
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• v.1 no.1
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• pp.23-27
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• 2012

Recently, devices like Personal Privacy Devices (PPD) are being employed to avoid the detection of one's location by GPS, and most PPD transmits swept CW signals. However, signals transmitted from PPD may interfere a precise location system based on GPS. Accordingly, in order to reduce interferences by PPD, a technique to locate an interferer is needed. In order to locate an interferer AOA method and TDOA method are generally used, TDOA method is known to be more accurate than AOA method. Unfortunately, TDOA method has a problem of ambiguity in obtaining measurements of swept CW interference. Thus, this paper design a localization algorithm based on TDOA method that can accurately locate an interferer transmitting swept CW signals by resolving problem of ambiguity. In addition, feasibility of the designed algorithm has been verified by simulation results.

• 제어로봇시스템학회:학술대회논문집
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• 2004.08a
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• pp.1814-1819
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• 2004

The purpose of this research is to improve the reliability of automobile navigation system that utilizes the magnetic compass for localization. On account of its sensitiveness against the dynamic external interference of the magnetic field, the electronic compass itself is not accurate enough to be used for the localization compared to the gyro-compass. To overcome this shortcoming, in this research, a robust electronic compass is designed by using two magnetic compasses to cancel out the dynamic interferences efficiently. That is, a dual compass predictive calibration algorithm against irregular external interference of magnetic field is newly proposed and implemented in this paper. When the dynamic interference can be eliminated from the electronic compass, it becomes much accurate than the gyro-based system that suffers from the accumulative drift error. The reliability and performance of the designed system have been verified through the real driving experiments.

• The Magazine of the IEIE
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• v.23 no.12
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• pp.115-125
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• 1996

This paper presents a new algorithm for the self-localization of a mobile robot using one degree perspective Invariant(Cross Ratio). Most of conventional model-based self-localization methods have some problems that data structure building, map updating and matching processes are very complex. Use of a simple cross ratio can be effective to the above problems. The algorithm is based on two basic assumptions that the ground plane is flat and two locally parallel sloe-lines are available. Also it is assumed that an environmental map is available for matching between the scene and the model. To extract an accurate steering angle for a mobile robot, we take advantage of geometric features such as vanishing points. Feature points for cross ratio are extracted robustly using a vanishing point and intersection points between two locally parallel side-lines and vertical lines. Also the local position estimation problem has been treated when feature points exist less than 4points in the viewed scene. The robustness and feasibility of our algorithms have been demonstrated through real world experiments In Indoor environments using an indoor mobile robot, KASIRI-II(KAist Simple Roving Intelligence).

• The Journal of the Acoustical Society of Korea
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• v.21 no.8
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• pp.686-694
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• 2002

This paper proposes an algorithm for estimating positions of array elements placed on a sea floor using acoustic signal in multipath ocean environment. The positions of array elements are estimated by using the travel times of m-sequence signal influenced by the multi-paths environment. The horizontal distance between source and receiver calculated based on the ray model. The proposed paper the algorithm is verified by both simulation data and field experiment in the Bast Sea.

• Transactions of the Korean Society of Automotive Engineers
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• v.16 no.2
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• pp.18-28
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• 2008

In inverse acoustic problem with nearfield sources, it is important to separate multiple acoustic sources and to measure the position of each target. This paper proposes a new algorithm by applying MUSIC(Multiple Signal Classification) to the outputs of discrete wavelet transformation with sub-band selection based on the entropy threshold, Some numerical experiments show that the proposed method can estimate the more precise positions than a conventional MUSIC algorithm under moderately correlated signal and relatively low signal-to-noise ratio case.

• Journal of Institute of Control, Robotics and Systems
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• v.11 no.1
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• pp.27-33
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• 2005

The purpose of this research is to improve the reliability of automobile navigation system that utilizes the magnetic compass for localization. On account of its sensitiveness against the dynamic external interference of the magnetic field, the electronic compass itself is not accurate enough to be used for the localization compared to the gyro-compass. To overcome this shortcoming, in this research, a robust electronic compass is designed by using two magnetic compasses to cancel out the dynamic interences efficiently. That is, a dual compass predictive calibration algorithm against irregular external interference of magnetic field is newly proposed and implemented in this paper. When the dynamic interference can be eliminated from the electronic compass, it becomes much accurate than the gyro-based system that suffers from the accumulative drift error. The reliability and performance of the designed system have been verified through the real driving experiments.

• 제어로봇시스템학회:학술대회논문집
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• 2005.06a
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• pp.872-876
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• 2005

We propose a real-time post processing of nonlinear amplified signal to improve voice recognition in remote talk. In the previous research, we have found the nonlinear amplification has unique advantage for both the voice activity detection and the sound localization in remote talk. However, the original signal becomes distorted due to its nonlinear amplification and, as a result, the rest of sequence such as speech recognition show less satisfactorily results. To remedy this problem, we implement a linearization algorithm to recover the voice signal's linear characteristics after the localization has been done.

• Journal of Information Technology Applications and Management
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• v.23 no.3
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• pp.87-97
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• 2016

This paper proposes a fast sound source localization method using a TDOA sign-based algorithm. We present an L-shaped microphone set-up which creates four major regions in the range of $0^{\circ}{\sim}360^{\circ}$ by the intersection of the positive and negative regions of the individual microphone pairs. Then, we make an initial source region prediction based on the signs of two TDOA estimates before computing the azimuth value. Also, we apply a threshold and angle comparison to tackle the existing front-back confusion problem. Our experimental results show that the proposed method is comparable in accuracy to previous three microphone array methods; however, it takes a shorter computation time because we compute only two TDOA values.